This invention relates to the securement of grounds and electrodes as they are used in the process of electric welding. In order to establish a proper electrical discharge from a welding rod and into a work piece, the work piece and rod or electrode must be well connected to the electrical energy source, and such connections are usually established by spring clamps and the like. However, spring biased clamps are not altogether satisfactory, since the springs often weaken and the spring pressure in conjunction with the dulling of the clamp jaws and/or teeth often results in a poor electrical contact, or lack of electrical continuity. In order to increase clamping pressures, "Vice-Grip" pliers have been employed so that the clamp teeth can be operated to bear into the work piece. Nevertheless, due to lack of pressure, dullness of the clamp teeth and because of scale such as oxides and the like, adequate connection remains a problem. This continuity problem is commonly sought to be corrected by striking the clamp jaws with a hammer in order to bury them into the work piece or onto the rod. It is a general object of this invention to provide a welder's grounding and rod clamp which has adequate pressure and ensures electrical continuity and which seldom if ever requires to be struck with a hammer or the like. It is obvious that hammering is detrimental, as it is not only time consuming but can be damaging to the work piece or rod and to the clamp members as well.
The purpose of employing "Vice-Grip" type clamps is that they are adjustable and quickly releasable. Adjustment relates to the thickness of the part to be clamped, and quick release relates to operation of a depressible release lever. This invention employs state of the art adjustment, it being an object here to greatly improve the so-called quick release function. With the prior art clamps, release is a two-handed operation for the welder who normally grips or handles the clamp with a single hand and operates the release lever with the other hand. To this end I have provided a welder's clamp which can be held in one hand and quickly released by thumb pressure without changing his hand grip. It is also an object of this invention to provide an alternate mode of quick release which conveniently enables bumping of the release lever. This latter mode of release can be used when a solid object is present against which the release lever can be bumped, thereby releasing the toggle link of the clamp.
A safety protection feature is to coat the clamp structure with a dielectric insulation material, not shown herein as as to better reveal the clamp structure. The coating is applied coextensively to the exposed exterior to be handled by the welder.
The typical work piece to which a ground must be established is a plate or sheet of metal, or any part having thickness with opposite sides that can be gripped. It is usual for the side of a part to be parallel, but not necessarily so, and accordingly electrical contact over a relatively small area is to be preferred, since contact over a large area could be unstable due to surface imperfection and shifting of the clamp caused thereby. It is therefore an object of this invention to provide a local or small area of contact which will accept pressure applied to a single tooth or to a limited number of teeth, as may be required.
Locking pliers, commonly known as "Vice-Grips", are characterized by short heavy jaws that inflexibly grip themselves onto a work surface. The spacing of the jaws is adjusted so that a pre-set spacing thereof is attained, and to which the jaws are operated by means of a toggle lever system. However, this type of locking pliers is unyielding and the set position often becomes loose; in which case electrical continuity is lost when this type of pliers is used as a welder's clamp. Therefore, it is an object of this invention to provide resilient jaws that can be pre-set and nevertheless yield to stress and changing part conditions, so that clamping pressure is maintained and electrical continuity is never lost. In practice, the yielding function for maintaining gripping pressure is by means of lengthening the jaws, whereby resilience from the pliers fulcrum inherently provides continued pressure at the clamping jaws.
Heretofore, ground clamps of the type under consideration have been bulky and cumbersome. That is, the heft of the clamping pliers must be substantial and of considerable length, and from which a ground conductor must be extended; and all of which is constructed in one longitudinal alignment. This results in awkward situations when work space is cramped, and it is often difficult if not impossible to conveniently attach a ground to a work piece. Accordingly, it is an object of this invention to arrange the clamp jaws and teeth in such a manner that the welder has several choices in the placement and/or disposition of the grounding clamp. With the present invention there are terminal clamp teeth as well as laterally extended clamp teeth, and all of which are readily available through manipulation and without adjustment, as circumstances require. For example, the grounding clamp of the present invention can be applied to lie alongside a work piece rather than project therefrom, thereby saving space without encroachment into working space.
A typical rod electrode is a small diameter elongate cylindrical member that is clamped between diametrically opposed jaws operated by a handle and an acuating lever disposed one over the other when held in a natural hand gripping position. In said natural gripping position it is desirable that the welding rod, or "stinger", project downwardly from the clamp. Therefore, it is an object of this invention to provide clamp jaws by which this quick releasable clamp can be held in a natural upright position with the handle over the actuating lever, and with the welding rod projecting downwardly, or forwardly in a normal manner.
Electric welding requires the use of heavy conductors in order to carry the high voltages and current rates involved. For example, a typical grounding or power cable is 5/8 inch diameter, made up of a multiplicity of conductor wires covered by an insulating sheath, short sections thereof being substantially inflexible. End terminals are usually soldered thereto and tend to fracture the wire conductors, since such terminals are tightly secured with screw fasteners or the like so as to be rigid with the frame of the clamp. Therefore, turning and twisting of the cable and state of the art clamps has resulted in damage to the ground conductor wires at their joinder to the clamp frame by the end terminal, it being an object of this invention to guide as well as to anchor the short section of cable immediate to the said end fitting attachment to the clamp frame. With the present invention, stress is removed from the end terminal so that the electrical connection thereof to the clamp frame remains tight.